As a battery module having batteries that are arranged side by side and held by battery holders, the one disclosed in Patent Document 1 is known.
The bipolar battery disclosed in Patent Document 1 includes frames (battery holders) that tightly hold a current collector. Each frame has a coupling portion for being coupled to adjacent other frames. The coupling portion has a protrusion and a recess, and the protrusion of each frame is inserted into the recess of the adjacent frame. The coupling portion has holes, which receives rod-like support bodies. The support bodies couple the frames and the current collectors to each other.